Delpy was born in Paris, the only child of Albert Delpy and Marie Pillet. Both her parents were actors in feature films and the avant-gardetheater, and her father was a theater director.
On the stages of Paris, Delpy's parents were involved in underground theater. At an early age, Julie was exposed to the arts. "I couldn't hope for better parents.At age fourteen Delpy obtained a role in the film Détective, directed by Jean-Luc Godard. Two years later, Delpy was cast in the title role in the 1987 film La Passion Béatrice (Beartrice), and used the money she earned to pay for her first trip to New York City. Delpy continued to make regular trips to New York during the next few years, before finally moving there in 1990. Delpy became an international celebrity after starring in the 1990 film Europa Europa. In the film, she plays a pro-Nazi girl, Leni, who falls in love with the hero, Solomon Perel, not knowing that he isJewish. She had to speak fluent German for the part.
Delpy was subsequently given offers to appear in several Hollywood and European films. In 1993, she was cast by director Krzysztof Kieślowskito play the female lead in Three Colors: White, the second film of Kieślowski's Trois Couleurs trilogy; Delpy also briefly appeared in the other films in the series in the same role.
Since then, she has starred in many American and European productions, including Disney's The Three Musketeers (1993) and Killing Zoe(1994). Delpy may be best known internationally for her co-starring role with Ethan Hawke in director Richard Linklater's 1995 film, Before Sunrise. The film received glowing reviews and was considered one of the most significant films of the independent film movement of the 1990s.
Delpy has also had an interest in a career as a film director since her childhood, and enrolled in a summer directing course at New York University. She wrote and directed the short film Blah Blah Blah (1995), which screened at the Sundance Film Festival. She made her feature length directorial debut in 2002, with a film entitled Looking for Jimmy, which she also wrote and produced. 2007 saw the release of 2 Days in Paris in which Delpy not only starred in the film (with Adam Goldberg), but also directed, wrote, edited, co-produced it and wrote the original music. The film also features Delpy's real-life parents, Marie Pillet and Albert Delpy, as her character's parents